Summary

The livers of rats fed no azo dye or equimolar levels of either 4-aminoazobenzene, 4′-methyl-4-dimethylaminoazobenzene, 4-dimethylaminoazobenzene, or 3′-methyl-4-dimethylaminoazobenzene for four weeks were homogenized and separated by differential centrifugation into nuclear, large granule, small granule, and supernatant fluid fractions. The original homogenate and the fractions were analyzed for protein, nucleic acids, riboflavin, and protein-bound aminoazo dye.

The non-carcinogenic dye, 4-aminoazobenzene, and the weakly carcinogenic dye, 4′-methyl-4-dimethylaminoazobenzene, produced little or no change in the composition of the liver.

The highly active carcinogen, 3′-methyl-4-dimethylaminoazobenzene, produced many of the same changes in the composition of the fractions as were observed previously with 4-dimethylaminoazobenzene, a moderately strong carcinogen, except that the changes were greater in magnitude. These changes included increased levels of protein and desoxypentosenucleic acid in the nuclear fraction, decreased contents of protein and pentosenucleic acid in the large and small granules, and a decreased amount of riboflavin in the large granules. In addition this powerful carcinogen increased the level of pentosenucleic acid in the nuclear fraction and the supernatant fluid. Many of the changes induced by feeding 3′-methyl-4-dimethylaminoazobenzene were so great as to make the liver very similar to hepatic tumor tissue in intracellular composition.

All of the dyes produced protein-bound aminoazo dye in each fraction of the liver cell. No correlation was evident between the intracellular distribution of bound dye and the carcinogenicity of the dye fed.

Footnotes

↵* This work was supported by grants from the National Cancer Institute, United States Public Health Service, and the Jane Coffin Childs Memorial Fund for Medical Research.